by Janice Lloyd, USA TODAY

by Janice Lloyd, USA TODAY

If Hurricane Sandy's wind damages your home or business, you might be facing another blow: Your share of the bill might be thousands of dollars higher than you expected.

Insurers require owners in some areas to pay a percentage of the replacement value of the property rather than a deductible in the event of hurricane damage, according to Mike Barry of the Insurance Information Institute.

"The key thing is, you're covered for wind damage,'' Barry says,"but you need to know your responsibility and the insurance company's. It's changed a great deal over the past 20 years."

Along coastal areas from Florida to Maine, the owner pays a percentage of the replacement value of the property rather than a traditional deductible in the event of hurricane damage, according to Barry.

The owner's responsibility is spelled out on the policy's declaration page. Here's how it works:

Your share: Insurers in coastal states sell homeowners insurance policies with percentage deductibles for storm damage instead of the traditional dollar deductibles, which are used for other types of losses, such as fire damage and theft.

With a policy that has a $500 standard deductible, for example, the policyholder must pay the first $500 of the claim out of pocket.

But percentage deductibles are based on the home's insured value. So if a house is insured for $300,000 and has a 5% deductible, the first $15,000 of a claim must be paid out of the policyholder's pocket.

Percentages range from 1% to 5%. People with beachfront property probably have higher percentages, Barry says.

Triggers: Your policy will say what prompts the percentage vs. the traditional dollar deductible to go into effect. In other words, it could be a Category 1 or Category 2 hurricane. Triggers vary by state and insurer, and may apply when the National Weather Service (NWS) "names" a tropical storm, declares a hurricane watch or warning or defines the hurricane's intensity.

The Atlantic Coast, the Gulf of Mexico and the Hawaiian islands are home to the U.S. counties most vulnerable to hurricanes. These counties account for nearly two-thirds of the nation's coastline population, according to the U.S. Census Bureau.

"As more people have moved to the coasts, it's become too expensive for the insurance companies to assume the cost of the hurricane damage,'' Barry says.

Hurricane Katrina in 2005 cost insurers $42 billion.

Flood damage resulting from storm surge caused by hurricanes is not covered under standard homeowners and renters insurance policies. However, flood coverage is available from the National Flood Insurance Program (NFIP) and from a few private insurance companies.

Damage to cars is covered under comprehensive insurance packages, which nearly 80% of people carry, according to the Insurance Information Institute. If a tree falls on your car or it's submerged in water, your comprehensive policy will cover it.

"Many people will decide not to have collision (coverage) on an older car,'' says Barry. "That will save them some money. But they should never drop comprehensive coverage."